The present invention relates to a new class of corrosion inhibitors. More specifically, the invention concerns novel compositions which reduce the attack of aqueous solutions of acids on metals of construction.
Many compositions have been proposed as corrosion inhibitors for ferrous metals in oil field applications, such as acidizing. Many of said compositions exhibit acceptable rates of inhibition under limited circumstances. See, e.g., the teaching of U.S. Pat. No. 3,077,454, which describes Mannich condensation products as corrosion inhibitors. However, it would be desirable to have a corrosion inhibitor composition which is useful in a broader number of situations. For example, the presence of H.sub.2 S in wells (sour wells) leads to unique corrosion problems in addition to the corrosion problems presented by the acidizing acid. Additionally, in certain applications it is necessary to employ special additives, such as demulsifiers or wetting agents, which often are not highly compatible with the corrosion inhibitor being employed, thereby leading to reduced corrosion protection. Thus, it would be desirable to have a corrosion inhibitor composition which could inhibit acid corrosion of ferrous metals even in the presence of H.sub.2 S, and which would be highly compatible with a large number of special additives.